The Massachusetts Department of Public Health Office of HIV/AIDS proposes to conduct HIV Behavioral Surveillance among four groups at increased risk for acquiring HIV infection: men who have with men (MSM), injecting drug users (IDU) individuals at heterosexual risk (HET) and Transgender individuals living in the three county Boston Division of the Metropolitan Statistical Area. The results will be used to plan statewide HIV/AIDS prevention programs and to 1) increase the number of persons at risk who know their HIV status, 2) decrease the number of new HIV infections and 3) improve the health and quality of life of HIV-infected and high-risk uninfected persons.